import tensorflow as tf

# tf.compat.v1.disable_eager_execution()  # Not neede when use explicit static graph

g = tf.compat.v1.Graph()
with g.as_default():
    x = tf.compat.v1.placeholder(name='x', shape=[], dtype=tf.string)
    y = tf.compat.v1.placeholder(name='y', shape=[], dtype=tf.string)
    z = tf.strings.join([x, y], name="join", separator=" ")

with tf.compat.v1.Session(graph=g) as sess:
    zv = sess.run(fetches=z, feed_dict={x: 'Hello', y: 'Betty'})
    print(zv)
